steel manufacturing

5/23/2018 Steel Manufacturing

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STEEL MANUFACTURING INDUSTRY


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TABLE OF CONTENTS

I. TerminologiesII. IntroductionIII. Manufacturing Process

i. Flowchartii. Brief discussion of the processiii. Equipment machineriesiv. Testing involve in the process

IV. Bibliography


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TERMINOLOGIES

AlloyIs a mixture of two or more elements in solid solution in which the majorcomponent is a metal.

CastingInvolves pouring liquid metal into a mould, which contains a hollowcavity of the desired shape, and then allowing it to cool and solidify.

Coke (fuel)Coke is the carbon product that is formed by the thermal distillationof coal at high temperatures in the absence of air in coke oven batteries. Coke isused in the blast furnace to provide a reducing atmosphere and is also a sourceof fuel.

CorrosionThe gradual destruction of material, usually metals, by chemicalreaction with its environment. In the most common use of the word, this meanselectro-chemical oxidation of metals in reaction with an oxidant such as oxygen.Rusting, the formation of iron oxides is a well-known example of electrochemical

corrosion.

Ferrous MetalsThe term "ferrous" is derived from the Latin word meaningcontaining iron". This can include pure iron, such as wrought iron, or an alloy

such as steel. Ferrous metals are often magnetic, but not exclusively.

Furnacea device used for heating. The name derives from Latin fornax, oven.

GangueSecondary materials consist of impurities of an earthly nature, such asrock, sand, and clay.

Hematite Also spelled as haematite, is the mineral form of iron(III) oxide (Fe2O3),one of several iron oxides. Hematite is a mineral, colour black to steel or silver-gray, brown to reddish brown, or red. It is mined as the main ore of iron.

Ingotsare a material, usually metal, that is cast into a shape suitable for furtherprocessing. Non- metallic and semiconductor materials prepared in bulk formmay also be referred to as ingots, particularly when cast by mould basedmethods.

IronA rarely found in metallic state, but occurs in form of various mineralcompounds, known as ores.

Iron OresAre rocks and minerals from which metallic iron can be economicallyextracted. The ores are usually rich in iron oxides and vary in colour from darkgrey, bright yellow, deep purple, to rusty red.

MagnetiteA black magnetic mineral, found in igneous and metamorphic rocksand as a separate deposit. It is a source of iron.


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Materials Scienceis an interdisciplinary field applying the properties of matter tovarious areas of science and engineering. This scientific field investigates therelationship between the structure of materials at atomic or molecular scalesand their macroscopic properties. It incorporates elements of applied physicsand chemistry.

Metal An element, compound, or alloy that is a good conductor of bothelectricity and heat.

MetallurgyA domain of materials science that studies the physical and chemicalbehaviour of metallic elements, their intermetallic compounds, and theirmixtures, which are called alloys. It is also the technology of metals: the way inwhich science is applied to their practical use. Metallurgy is distinguished fromthe craft of metalworking.

Miningis the extraction of valuable minerals or other geological materials fromthe earth, from an ore body, vein or (coal) seam. This term also includes the

removal of soil. Materials recovered by mining include base metals, preciousmetals, iron, uranium, coal, diamonds, limestone, oil shale, rock salt and potash.Mining is required to obtain any material that cannot be grown throughagricultural processes, or created artificially in a laboratory or factory.

Nitrogenimproves strength , hardness, and machine ability; in aluminium-deoxidized steels, it controls the size of inclusion and improves strength andtoughness; decrease ductility and toughness.

Non-ferrous metalA metal that is not ferrous, that is, any metal, including alloys,that does not contain iron in appreciable amounts.

OresA type of rock that contains minerals with important elements includingmetals. The ores are extracted through mining; these are then refined to extractthe valuable elements.

Oxygen slightly increase strength in rimmed steel; severely reduces toughness.

Phosphorus improves strength, harden ability, corrosion resistance and machineability, severely reduced ductility and toughness.

Pig Ironthe first product in the process of converting iron ore into useful metal by

using blast furnace. The molten metal from the blast furnace was earlier used tobe poured into small sand moulds, arranged like a litter of small pigs around amain channel. The solidified metal was called pig and hence such iron wasnamed pig iron.

Slagis the vitreous mass left as a residue by the smelting of metallic ore.


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SmeltingA form of extractive metallurgy; its main use is to produce a metal fromits ore. This includes production of silver, iron, copper and other base metals fromtheir ores. Smelting uses heat and a chemical reducing agent to decompose theore, driving off other elements as gasses or slag and leaving just the metalbehind.

Steel An alloy made by combining iron and other elements, the most commonof these being carbon.

TaconiteA fine-grained sedimentary rock containing magnetite, haematite, andsilica, mined as a low-grade iron ore.

Tundish a refractory- lined intermediate pouring vessel where impurities in metalare skimmed off.

TuyereAlso can be spelled as tuyre, is a tube, nozzle or pipe through which air is

blown into a furnace or hearth.


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INTRODUCTION

The study of metal alloys is an important part of materials science. It signifies themanufacturing of structural materials such as iron, steels and other alloys formed.With these varieties of metals formed with alloying, my chosen area for study is

about Steel manufacturing, since it plays an important part in metal industries inwhich steel is the initial needed material for production of enhanced alloys.

Steel is categorized as a Ferrous Material and it is basically an alloy of iron andcarbon, where the carbon content depends on the quality of an alloy to beproduced. Higher the carbon content, the higher the harden ability, strength,hardness, and wear resistance of the steel. But ductility, weld ability andtoughness are lowered. Various quantities of elements added to steel control thequality of such properties on these steel. Knowing first the principles behindsteelmaking processes are essential for us to have a perceptive of thecharacteristics of steel being produced by the methods Ive opt for.

Before proceeding to steelmaking, iron must be first manufactured. Beginningwith raw materials, iron ores, limestone, and coke are the basic materials in ironmaking. Ore dressing processes are conducted for the concentration of the ironores. These materials are processed in the blast furnace then produce pig ironand sent to Basic oxygen furnace to proceed in the steelmaking process.Additional treatments are applied to the steels and continuously cast, solidifyingthe steel forming the blooms and billets which is now our primary materials.However, further examination of defects in the steel is conducted and broughtto testing machines to assure its capacity to stress. Conceded steels are sentinto mills for further processing.

Due to the rapid growth of technology, Industries similar to this of steel

manufacturing will soon become the foundation for a developing country. Andthis will cause higher demands for the need of professionals in the related field.As engineering student, having knowledge about steel manufacturing is a goodstart and soon be applied in the future.


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RAW MATERIALS

The three primary materials used in iron- steel manufacturing are the iron ores,

limestone and coke. The main common iron ore used is in the form of oxide

known as hematite which its colours varies from blackish brown to brick red and

this is the most important ore found in the United States. Another raw materialwhich is used as fuel is known as coke. A light absorbent material made from

coal which is placed in the brick linings of the furnace and heated to a high level

of heat required for chemical reactions and then cooled after with water in

quenching towers. Lastly, materials that is used as a flux is known as the

limestone, which removes impurities such as phosphorous, silica, sulphur,

manganese and silicon. Limestone reacts chemically and combines with the

impurities forming a slag.


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FLOWCHART

Raw materials

Blast Furnace: Produces molten pig iron

Pig iron casting


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Basic Oxygen Furnace: Produces molten metal

Steel refining facility

Billets and Blooms

Continuous casting


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BRIEF DISCUSSION OF THE PROCESS

Iron ores are extracted in ground by drilling machines before it can be used in

the process. Iron containing oxides known as hematite is the most commonly

used iron ore. After it is mined, the iron ores are crushed into fine particles and

concentrated even more by means of removing the impurities which containsusually of phosphorus , silica , sulphur , manganese and silicon. Coke is then

used as the fuel to melt the iron. When the iron ores melted, the limestone

combines with the impurities forming a slag then floats at the top of the molten

metal and removed separately afterwards.

After such processing, the concentrated ores are then brought to the blast

furnace. This furnace is a tower like lined with refractory materials which are

heat- resistant bricks. During operation, the top of the blast furnace is sealed with

double bells and hoppers for fuel, ore, and flux to supply continuously. A very hot

air usually at 1100F or higher is blasted at the bottom of the furnace and inthrough nozzles called tuyeres. Iron ore, coke and limestone are transmitted to

the top of the furnace and dropped in layers. The coke burns due to the intense

heat around the tuyeres and then forms a carbon monoxide gas. The carbon

monoxide reacts with the iron ore, coke, and limestone, reducing it, forming the

iron ore to metallic iron. Slag containing the unions of limestone flux with sulphur,

alumina, silica, and other impurities floats on top of the melted iron. The iron and

slag are drawn off separately fro the bottom of the surface. There are two tap

holes, top holes where the molten slag are carried off to ladles for disposals and

the bottom holes where melted iron flows to the metal mold and will be cast to

form pig irons.

After casting of the pigs, hot metals are poured into large refractory- lined ladle

and are sent directly to the basic oxygen furnace for the steelmaking. The vessel

is filled or charged with the pig iron and scrap. Additions of burnt lime or

dolomite are fed into the vessel to form slag which absorbs the impurities during

the blowing process. He oxygen is vigorously blown by the lance which refines

the molten metals by an oxidation process in which iron oxide is first produced.

Then, the oxide reacts with the carbon that dissolved in the molten metal

producing carbon monoxide and carbon dioxide causing the temperature to

rise up to 1700C. Virtually at end of the process, the temperature is measuredand samples of steel are taken for further examination. The vessel is then tilted by

tapping the furnace to pour the steel into giant ladles and the vessel is tilted

again to the opposite direction where slag are poured off separately and

cooled.

Steels are further refined in the ladle furnace by the vacuum processing which

removes the gaseous impurities and this process will produced high quality steels.


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After undergoing to the ladle treatments, ladles are transported to the top of the

casting machines. Molten metal is cleaned and equalized in temperature by

blowing nitrogen gas to it for about five to ten minutes. Molten metal is now

poured into a refractory- lined pouring vessels which is the tundish and flows

through another shroud pipe onto the mould. Depth of the mould depends on

the casting speed and section size. Primary cooling of the mould is provided by

water sprays along the travel path of the solidifying metals. Lubricants are added

to the metals in the mould to reduce friction and prevent the metals from

sticking to the moulds. In the strand, metals within this wall are still molten. A

water-cooled roller supports the wall from the ferrostatic pressure of the still

solidifying metal. Secondary cooling process is done to increase the rate of

solidification. Solidify metals finally exited the spray chambers. Blooms and billets

are now formed.


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EQUIPMENT MACHINERIES

Preference of machines required for the steel manufacture must be first ensure

the highest precision, reliability and productivity of the equipments to be

operated. Here are some of the machineries will be used in the production and

their functions.

BLAST FURNACE STOVE

Fig.1: A blast furnace shell constructed

by BSIET in Beijing, China Source: Beijing

Shougang International Engineering

Technology Co.,Ltd.

A brick-lined regenerator

enclosed in a circular steel shellwith a flat bottom and a dome-shaped top. Their purpose is topreheat the blast to a blastfurnace.

LADLES TRANSFER CAR

Fig.2: A ladle car carrying molten iron

Source: India e-Classifieds

A welded steel ladle mounted on arailway car for transporting moltenpig iron to the mixer in a steel-smelting plant or to a castingmachine. The interior is lined withrefractory brick. Locomotivetraction is used to move the car;five or six cars are coupled

together.


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BUSTLE PIPE

Fig.3: A bustle pipe placed inthe construction of the blastfurnace. Source: China SteelMachin ery Cor po rat io n.

the outside pipe that

supplies the blast to the

tuyeres in a blast furnace

COKE OVEN

Fig.3 Source: CONSOL Energy Inc.

An oven for the conversion of coal into coke byheating the coal in the absence of air to distil the

volatile ingredients.


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BIBLIOGRAPHY

Degarmo, E. Paul; Black, J T.; Kohser, Ronald A. (2003).Materials and Processes inManufacturing(9th ed.). Wiley.

Materials Science and Engineering: An Introduction William D. Callister, Jr.Department of Metallurgical Engineering The University of Utah.

Mathews, F.L. & Rawlings, R.D. (1999). Composite Materials: Engineering andScience. Boca Raton: CRC Press.

Singh, D. K..Fundamentals of Manufacturing Engineering. First Ed. Taylor & Francis

Group. Ane Books India. New York, USA. 2008

Budinski, Kenneth & Michael. Engineering Materials: Properties and Selection, 9th

Ed. Pearson Education, Inc., Upper Saddle River, New Jersey, 1996

Clark, D. S., Engineering Materials and Processes. 3 rdEd. International Textbook

Co., Scraton, Pennsylvania. 1967

Kalpakjian, Serope. Manufacturing Engineering. 3rdEd. Addison-WesleyPublishing

Co., 1995

steel manufacturing

Documents

metallic iron

wrought iron

pure iron

source of iron

formation of iron oxides

iron oresare rocks

main ore of iron

manufacturing processi